The U.S. Navy says it is holding 16 suspected pirates it captured off the coast of Somalia aboard a warship while awaiting orders to move the suspects to Kenya for prosecution. The agreement to hand over suspected pirates to Kenya was reached last month between the U.S. and Kenyan governments. But, the agreement has raised questions and concern from a leading human rights group.

The U.S. Navy seized seven men on Tuesday and nine more on Thursday after responding to distress calls from vessels sailing through the Gulf of Aden. In both incidents, a boarding team from the naval ship USS Vella Gulf found automatic rifles, rocket-propelled grenade launchers and other weapons aboard the skiffs used by the suspected hijackers.

The 16 men, believed to be Somali nationals, are expected to be held aboard another U.S. warship until they can be handed over to authorities in Kenya for prosecution.

Last month, Kenya signed a memorandum of understanding with the United States to accept suspected pirates captured by U.S. forces and try them on Kenyan soil. Details of the agreement were not made public and the U.S. ambassador to Kenya, Michael Ranneburger, said talks were still ongoing on how to implement it.

Ben Rawlence of the New York-based Human Rights Watch tells VOA that his group is concerned that in its eagerness to bring pirates to justice, the United States may be overlooking a critical problem in Kenya, which is likely to affect the way pirates are detained and prosecuted.

"There are major, major problems with the Kenyan justice system," he said. "No one really is guaranteed the right to a fair trial in that system. The police have a terrible record of long periods of detention without trial, terrible conditions in the prisons, very poor record of access to legal representation, interminable delays in the court process. The Kenyan justice system is in a terrible state."

In 2007, after the fall of the Islamic Courts Union in Somalia, Muslim and human rights groups, including Human Rights Watch, sharply criticized Kenya for what they said was the arbitrarily detention of at least 150 people suspected of being terrorists. Human Rights Watch said that as many as 85 people were secretly deported from Kenya to Somalia at the request of U.S., Somali, and Ethiopian governments.

Rawlence says charges of mistreatment or abuse of suspected Somali pirates brought to Kenya under a vague, little publicized agreement could again stir up anger and resentment among Muslims in Somalia and the region.

"There is a very real risk that this agreement might be perceived as an attack on Muslims. Anything that the United States does is subject to a high degree of suspicion," he said. "Any kind of secret agreement is bound to spawn all sorts of speculation about what sort of nefarious practices are going on. So, it is in the interest of the U.S. and Kenya to be as open and as transparent as possible about this."

Eight Somalis captured last November by the British navy are in jail in Kenya accused of trying to hijack a Danish freighter. The trial began in December but was postponed until January 14. It has not yet resumed. The accused pirates' attorney has complained that the men are being mistreated in prison.

In December, Kenya also signed an agreement with Britain to prosecute suspected pirates captured by the British.